Book excerpt: Interest in digital filtering techniques continues to grow with the general increase in the use of digital processors. The first five chapters of this book form an introduction to digital filtering, while the following four extend the subject to cover the filtering of noisy data in order to extract a signal. The book is suitable for use by final year undergraduates, or for MSc and MEng courses. The text includes worked examples and problems with solutions. In this new edition, some new practical material and problems are added, and there are new introductory sections on topics such as wave digital filters and multirate filters. This continues to be the book that introduces both the theory of digital filters and their use in extracting information from noisy data, in an optimal way.